The present application claims priority to Japanese Patent Application No. 2001-017936, filed Jan. 26, 2001, and Japanese Patent Application No. 2001-361720, filed Nov. 27, 2001. The contents of those applications are incorporated herein by reference in their entirety.
1. Field of the Invention
The present invention relates to a linear oscillation motor, a controlling apparatus for a linear oscillation motor and a method for controlling a linear oscillation motor.
2. Discussion of the Background
Japanese Unexamined Patent Publication 8-331826 discloses a method for controlling a linear oscillation motor in which a controlling apparatus supplies current compatible to the moving direction of a movable element in the linear oscillation motor as a detector detects the moving direction of the movable element. In other words, this controlling device begins current supply somewhere between the point where the movable element reverses its moving direction and the mid-point of the oscillatory movement. Thus, the oscillatory movement of the movable element is not interfered by the operation of the controlling apparatus.
Also, Japanese Unexamined Patent Publication 10-243622 discloses a method for controlling a linear oscillation motor in which a controlling apparatus drives a movable element of the linear oscillation motor according to a fixed frequency when the movement of the movable element cannot be detected. According to Japanese Unexamined Patent Publication 10-243622, a frequency detected while the movement of the movable element can be detected is utilized for the fixed frequency.
Furthermore, Japanese Unexamined Patent Publication 2001-16892 discloses a method for controlling a linear oscillation motor in which movement of a movable element of the linear oscillation motor, such as position, velocity and/or acceleration, is determined by detecting voltage induced in a winding of an electromagnet in the linear oscillation motor. According to Japanese Unexamined Patent Publication 2001-16892, since only the voltage induced due to the movement of the movable element is detected, a period during which current supply to the winding is cut off is set up in a duration during which the movable element is expected to reverse its moving direction.
The contents of those publications are incorporated herein by reference in their entirety.
According to one aspect of the present invention, a controlling apparatus for controlling a linear oscillation motor includes a sensor and a controller. The motor has a movable element and a stator one of which includes an electromagnet with a winding. The sensor is configured to detect movement of the movable element. The controller is configured to intermittently supply electric power to the winding of the electromagnet to move the movable element reciprocally and linearly. The controller is configured to begin each intermittent supply of electric power to the winding at a timing before a dead center of the movable element based on an output of the sensor.
According to another aspect of the present invention, a linear oscillation motor includes a movable element, a stator, one of the movable element and the stator comprising an electromagnet with a winding, a sensor configured to detect movement of the movable element, and a controller configured to intermittently supply electric power to the winding of the electromagnet to move the movable element reciprocally and linearly, the controller being configured to begin each intermittent supply of electric power to the winding at a timing before a dead center of the movable element based on an output of the sensor.
According to another aspect of the present invention, a linear oscillation motor includes a rotor, a stator, one of the rotor and the stator comprising an electromagnet with a winding, a sensor configured to detect movement of the movable element, a controller configured to intermittently supply electric power to the winding of the electromagnet to rotate the rotor periodically changing a rotational direction of the rotor, the controller being configured to begin each intermittent supply of electric power to the winding at a timing before a dead center at which the rotor changes its rotational direction, and an oscillatory element configured to be moved reciprocally and linearly by rotation of the rotor.
According to yet another aspect of the present invention, a method for controlling a linear oscillation motor having a movable element and a stator one of which comprises an electromagnet with a winding, includes detecting movement of the movable element, supplying electric power intermittently to the winding of the electromagnet to move the movable element reciprocally and linearly, and beginning each intermittent supply of electric power to the winding at a timing before a dead center of the movable element based on an output of the sensor.